Storage system storing a plurality of disk files which correspond to a plurality of virtual disks and access control method thereof

1. An access control method for use in a storage system, the storage system connecting to at least one hypervisor server and storing a plurality of disk files which correspond to a plurality of virtual disks respectively, the disk files being stored as a file system in a storage unit of the storage system, the access control method comprising: receiving, at the storage system, a first I/O request from the at least one hypervisor, wherein the first I/O request is configured to access a first disk file of the disk files; operating, by the storage system, a first I/O operation of a first virtual disk of the virtual disks according to the first I/O request; reading, by the storage system, a quality of service (QoS) data of the first disk file, wherein the QoS data comprises an input output per second (IOPS) information and an I/O bandwidth information, wherein the QoS data is recorded with the first disk file or recorded with a dictionary of the first disk file, and the first disk file or the dictionary of the disk file is stored in the storage unit of the storage system; determining, by the storage system, a first delay period according to the IOPS information of the first disk file and the I/O bandwidth information of the first disk file; and suspending a subsequent I/O operation of the first disk file for a time duration associated with the first delay period to balance an I/O QoS of the first virtual disk by transmitting, by the storage system, a first I/O response to the at least one hypervisor only after expiration of the first delay period has passed.

2. The access control method as claimed in claim 1 , further comprising the following steps after the QoS data is recorded with the dictionary of the first disk file: receiving, at the storage system, a second I/O request from the at least one hypervisor, wherein the second I/O request is configured to access a second disk file of the disk files; operating, by the storage system, a second I/O operation of a second virtual disk of the virtual disks according to the second I/O request; reading, by the storage system, the QoS data of the second disk file from the dictionary, wherein the first disk file and the second disk file are stored in the dictionary; determining, by the storage system, a second delay period according to the IOPS information of the second disk file and the I/O bandwidth information of the second disk file; and suspending a subsequent I/O operation of the second disk file for a time duration associated with the second delay period to balance an I/O QoS of the second virtual disk by transmitting, by the storage system, a second I/O response to the at least one hypervisor only after expiration of the second delay period has passed.